Kestra's local internal-storage backend improperly limits pathname traversal by validating user input before converting Windows backslashes to forward slashes. This allows an authenticated user with the lowest privilege role to bypass the traversal check by using backslash sequences (e.g., ..\..\..\), which are later normalized to ../../../ just before file access. Consequently, the attacker can read any file readable by the Kestra process, including sensitive tenant data, secrets, and environment variables, violating multi-tenancy and storage isolation. The vulnerability is addressed in Kestra versions 1.0.45 and 1.3.23.

An attacker with authenticated access at the lowest privilege level can read arbitrary files on the server filesystem accessible to the Kestra process. This includes all tenants' data, stored secrets, mounted secret files, and environment variables containing credentials. This results in a complete breach of Kestra's storage isolation and multi-tenancy boundaries, potentially exposing sensitive information and credentials.

This vulnerability is fixed in Kestra versions 1.0.45 and 1.3.23. Users should upgrade to at least these versions to remediate the issue. No additional mitigation is indicated in the vendor advisory.